Which cleaning method allows for 5% staining in 5% of each area during the cleaning process?

The correct answer relates to SSPC-SP 10, which is the specification for "Near-White Metal Blast Cleaning." This cleaning method permits a specific degree of staining, allowing for up to 5% staining in 5% of each area cleaned. This means that while the aim is to achieve a very high level of cleanliness by removing rust, mill scale, and previous coatings, there is a tolerance for some remaining staining, which is significant when preparing surfaces for further treatment, like painting.

This specification is essential in certain industrial applications, including marine and heavy industrial settings, where achieving a “near-white" finish is desired for optimal adhesion and performance of subsequent coatings. The presence of minimal staining is acceptable as it does not adversely affect the coating's ability to adhere or protect the substrate when applied correctly.

Other cleaning methods listed have different standards and requirements regarding surface cleanliness and staining levels. Understanding these nuances helps in selecting the appropriate cleaning method for various applications in corrosion control and surface preparation.